Quantitative Aptitude - Arithmetic Ability Questions

If the speed of a boat in still water is 20 km/hr and the speed of the current is 5 km/hr, then the time taken by the boat to travel 100 km with the current is

The average height of 30 boys out of a class of 50 is 160 cm. If the average height of the remaining boys is 165 cm, the average height of the whole class (in cm) is:

A wholesaler sells a watch to a retailer at a gain of 20% and the retailer sells it to a customer at a loss of 10%. If the customer pays Rs 874.8, what had it cost the wholesaler?

A thief is stopped by a policeman from a distance of 250 metres. When the policeman starts the chase, the thief also starts running. Assuming the speed of the thief as 5 km/h and that of police man as 7 km/h, how far the thief would have run, before he is over ­taken?

If 35% of A is equal to 60% of B, then what is the ratio of A and B?

In each of the following questions two equations I and II are given. Solve both the equations and give answer:
$$\begin{gathered} I. x2+2x-195=0 \\ II. y2+30y+225=0 \end{gathered}$$

The third proportional of two numbers 4 and 20 is

If (4/5)A = 3B = (2/3)C, then what is A : B : C?